The Bronx-Whitestone Bridge, as shown in this 2003 photo, carries I-678 between the Ferry Point section of the Bronx and Whitestone, Queens. This photo was taken from the small Queens enclave of Malba. (Photo from wirednewyork.com.)

Type of bridge:Construction started:Opened to traffic:Length of main span:Length of side spans:Length, anchorage to anchorage:Total length of bridge and approaches:Width of bridge:Number of traffic lanes:Height of towers above mean high water:Clearance at center above mean high water:Steel used in towers:Steel used in suspended structure:Reinforcing steel used:Number of cables:Diameter of each of two cables:Total number of wires per cable:Length of each cable:Total length of wires:Weight of cables and suspenders:Total steel used on bridge:Concrete used in anchorages:Concrete used in tower piers:Concrete used in roadway and approaches:Total concrete used on bridge:Cost of original structure:

PROPOSING A NEW QUEENS-BRONX SPAN: In 1905, speculators proposed construction of a bridge over the East River from Whitestone, Queens to Ferry Point in the Bronx. In anticipation of the bridge, developers built the upscale neighborhoods of Malba, Beechhurst in the northern Queens community of Whitestone, along the East River shoreline. Facing opposition from area residents, who feared that the rural character of Queens would be destroyed, the proposed bridge was shelved.

Nearly a quarter century later, in 1929, the influential Regional Plan Association (RPA) revived plans for a fixed crossing between north-central Queens and the Bronx. The bridge, which was to be part of an "inner belt" in New York's circumferential highway system, would enable motorists to travel between Long Island, upstate New York and New England without passing through high-density areas in western Queens. On February 25, 1930, as part of his plan to expand his parkway system into New York City, Robert Moses, who served as New York City parks commissioner and arterial coordinator, proposed a "Ferry Point-Whitestone Bridge" that would enable motorists from the Bronx and Westchester to reach his Long Island state parks.

As the 1930s progressed, Moses had additional reasons to construct the Bronx-Whitestone Bridge. First, when it opened in 1936, traffic filled the eight lanes of the Triborough Bridge between Manhattan, the Bronx and Queens. The bridge was to provide relief for the Triborough Bridge. Second, the bridge was to provide a link from the north to the new airport at North Beach, which eventually became known as LaGuardia Airport. Finally, and perhaps most importantly, the bridge was to provide a direct link for upstate New York and New England motorists to reach the 1939-1940 World's Fair, which Moses chaired.

Moses received authorization to build the Bronx-Whitestone Bridge from the New York State Legislature in April 1937. The new bridge was to be administered by Moses' new Triborough Bridge Authority.

Still, the bridge proposal ran into opposition. Local residents were displeased at the quick decision by Moses to raze 17 homes in Malba. Moses defended his decision, responding that the condemnation was necessary to complete the project on time. Objections were also raised by the RPA, which said that the bridge should not be built unless provisions were made for rail transit. While the RPA said that the transit tie-in would not have to be immediate, the bridge structure would have to be strong enough to handle both vehicle and rail traffic. To Moses' favor, the RPA had no serious allies on its proposal.

The Bronx-Whitestone Bridge in 1940, one year after it opened. Note the lack of stiffening trusses and cable stays. The corrective measures were undertaken in the mid-1940s after the collapse of the Tacoma Narrows Bridge. Proposed improvements recently announced by MTA Bridges and Tunnels will restore the bridge to its original beauty. (Photo by Triborough Bridge and Tunnel Authority.)

DESIGN AND CONSTRUCTION: Since the bridge had to be completed in time for the opening of the World's Fair in April 1939, construction proceeded on a tight schedule. The famed bridge designer Othmar Ammann introduced a number of innovations that slashed construction time and produced an efficient structure.

The two 377-foot-steel towers, which were erected in only 18 days, were the first to employ a rigid-frame design without any diagonal cross bracing. These towers were constructed on reinforced piers that rest on solid rock. Each tower is built of two columns of closed-box construction, connected at the top and just below the deck with hemispheric arch portal struts. The two suspension cables rest on saddles atop the towers. Protective housings not only protect the saddles, but also serve as navigational lanterns.

The two 3,965-foot-long suspension cables support the 2,300-foot main span (which was at the time of opening the fourth longest in the world) some 150 feet over the East River. Each cable, which measures 21¾ inches in diameter, contains 37 strands of 266 galvanized steel wires. Fixed cables allow the towers to bend as conditions required.

Even the anchorages reflected Ammann's simplicity. Instead of employing extraneous architectural embellishments, he simply continued the curve of the cables for the external shape of the exposed concrete anchorages. Each of the anchorages, which measure 110 feet wide by 180 feet long by 110 feet high, weighs approximately 58,000 tons.

Perhaps the most innovative, and most controversial design characteristic was the absence of stiffening trusses. Instead, Ammaan employed a flexible steel-plate girder reinforcing system. As originally constructed, the plate girder deck was only 11 feet deep, giving the bridge a depth-to main span ratio of 1:209. During construction of the deck, prefabricated concrete roadway slabs were encased in reinforced steel. The raising of the deck began at each tower and proceeded simultaneously toward midspan and the approach roads. Overall, this innovative design not only gave the bridge a more streamlined appearance, but also cost savings of $2 million.

Finally, the approach viaducts to the Bronx-Whitestone Bridge consist of continuous plate-girder spans carried on reinforced concrete piers. In the original Moses design, the pastoral character of the parkway approaches gave way to the Art Deco modernity of the suspension bridge.

Leading up to the bridge along the original parkway approach. Until the late 1960s, wooden lightposts adorned the approaches. (Photo by Triborough Bridge and Tunnel Authority.)

"(The Bronx-Whitestone Bridge)… is architecturally the finest suspension bridge of them all, without comparison in cleanliness and simplicity of design, in lightness and absence of pretentious ornamentation. Here, if anywhere, we have pure, functional architecture." - Robert Moses, at the Bronx-Whitestone Bridge ribbon-cutting ceremony

THE BRIDGE OPENS: The Bronx-Whitestone Bridge was completed on April 29, 1939, six months ahead of schedule and only 23 months after construction began. The $19.7 million in construction costs were fully financed by Triborough Bridge Authority bonds, which were backed by the bridge's 25-cent tolls. When the bridge opened, it carried four lanes of traffic and two pedestrian walkways between the Bronx and Queens.

With its sleek, efficient Art Deco design, the bridge also won acclaim from architects, as well as from Mayor Fiorello LaGuardia:

Here, completed, we have one of the many monuments of an industrial country that confronted hardship by creating work. There she stands in all her beauty, awaiting dedication!

During 1940, its first full year of operation, the Bronx-Whitestone Bridge carried approximately 17,000 vehicles per day. In addition to new parkways, new recreational areas - Francis Lewis Park in Queens and Ferry Point Park in the Bronx - were developed for the bridge.

A POTENTIAL DESIGN FLAW: Soon after its opening, the bridge was found to have design flaws. The Tacoma Narrows Bridge in Tacoma, Washington, which employed a steel-plate girder deck stiffening system similar to that found on the Bronx-Whitestone Bridge, collapsed during a windstorm in 1940. In the aftermath, the Federal government spearheaded a blue-ribbon commission to investigate the collapse of "Galloping Gertie." The commission came to the following conclusions:

The deck of the original Tacoma Narrows was too shallow. With a deck depth of only eight feet and a main span of 2,800 feet, the depth-to-main span ratio was 1:350.

Moreover, the deck of the Tacoma span was too narrow. The deck width-to-main span ratio was 1:72 for the Tacoma Narrows Bridge, versus 1:33 for the George Washington Bridge and 1:31 for the Bronx-Whitestone Bridge.

Finally, the side spans of the Tacoma span were too long relative to the main span, and the cables were anchored a considerable distance beyond the side spans. A more favorable ratio may have provided more stability.

While Ammann believed that the Bronx-Whitestone Bridge was safe, he was aware that the span was subject to oscillation during high winds. In an effort to enhance the deck's stability, eight cable stays were installed from the towers to the decks in 1940. However, this did not stop the bridge's movement: the span was temporarily closed in 1943 when the bridge oscillated during a windstorm. Under orders from Moses, Ammann oversaw the retrofitting of two 14-foot-high stiffening trusses atop the 11-foot-high longitudinal deck. At the time of the retrofit, the six traffic lanes were widened, and the pedestrian walkways were eliminated.

In his autobiography Public Works: A Dangerous Trade, Moses recalled the design modification process as follows:

Othmar Ammann kept saying in his best Swiss brogue, "The britch is safe, the britch is safe," and we kept saying, "That doesn't make a damned bit of difference if drivers won't use it." Studies of wind pressures were made, and tests were speeded at a laboratory in Princeton. The first remedial step, in which I never had any confidence, was to install diagonal cables leading from the towers down to the girders on the road. It was like lifting a man up by his suspenders. Cables leading to the tower bases would obviously have had more effect in holding down the roadway, but Army Engineer rules prevented narrowing the horizontal clearance of the navigational channel.

In the end, stiffening the bridge by adding 14-foot-high trusses over the plate girders proved to be the only feasible answers. These huge trusses immediately dampened the vertical motion, but they detracted from the extreme simplicity and airy, gossamer lightness of the entire structure. The bridge was widened by removing the sidewalks to provide six lanes of adequate width, and the correction of vertical motion appeared to most travelers and observers to be an incident.

The stiffening trusses provided an additional level of stability, albeit at a price of aesthetics. Nevertheless, the deck of the Bronx-Whitestone Bridge tended to sway more than most suspension bridges. On November 12, 1968, the bridge swayed vertically by as much as ten inches during a Nor'easter in which winds gusted as much as 70 miles per hour. The incident closed the span for five hours during the morning rush.

Ralph Herman, contributor to nycroads.com and misc.transport.road, provides this story on the Bronx-Whitestone Bridge as follows:

When the bridge began to sway, motorists stalled in traffic abandoned their vehicles mid-span and ran down the roadway toward the shoreline. The Triborough Bridge and Tunnel Authority (TBTA) had to close the Whitestone Bridge at the height of the morning rush hour because of the abandoned vehicles, as well as obvious concern by the public about the integrity of the bridge. I also remember the TBTA engineers checked the bridge, then had their public relations people assure the public the bridge was safe. But because of a design flaw, the TBTA admitted it would sway more than the other New York area suspension bridges.

George Schoepfer, deputy chief engineer at the TBTA, responded in The New York Times:

All suspension bridges sway in the wind. If they didn't have give, they would snap. The reason that motorists noticed the sway today is because they were sitting in stalled cars. They felt it move. They don't notice it much when driving.

Between 1986 and 1988, the Bronx-Whitestone Bridge was stabilized further when engineers installed a mass damper system. Commonly found in skyscrapers, the mass damper system is designed to protect the span against dangerous oscillations. The mass damper system uses torsion springs measuring 240 feet long, mass blocks weighing 25 tons each, and multiple disc brakes to disperse more than 200 horsepower. They work independently of outside intervention whenever bridge motion due to wind exceeds a pre-determined threshold.

These 2000 photos show the Bronx-Whitestone Bridge (I-678) heading north from Queens into the Bronx. (Photos by Jim K. Georges.)

MAINTAINING A GREAT STRUCTURE: The Bronx-Whitestone Bridge proved an important component of the "Belt System," the circumferential parkway that connects the bridge with Queens and Brooklyn, and links with the Long Island parkway system. It also proved crucial in the development of similar parkway systems in upstate New York and Connecticut.

For many years, trucks and buses had to enter the Bronx-Whitestone Bridge at ramps near the Bronx and Queens approaches. This was because the Hutchinson River Parkway continued north into the Bronx, while the Whitestone Parkway continued south into Queens. In February 1959, the Whitestone Bridge was given the I-678 designation (after the preliminary I-595 and I-695 designations were rejected). To allow for the commercial traffic required for inclusion in the Interstate system, the Bronx and Queens approaches were reconstructed from parkway to expressway standards.

When the Throgs Neck Bridge opened in January 1961, traffic volume on the Bronx-Whitestone Bridge dropped from the pre-Throgs Neck level of 30 million vehicles per year. However, this statistical drop would not last long, and by the 1970's, volume on the Bronx-Whitestone exceeded its pre-Throgs Neck level.

The Bronx-Whitestone Bridge, which today has the 23rd longest main suspension span in the world, carries approximately 110,000 vehicles per day (AADT).

The Bronx-Whitestone Bridge, as shown from Francis Lewis Park in Whitestone, Queens in this 1998 photo. Design modifications -- specifically, the addition of a Warren truss and diagonal stays -- were made on the bridge to help it better withstand stress from heavy loads and high winds. (Photo by Steve Anderson.)

RESTORING THE BRIDGE TO ITS ORIGINAL BEAUTY: In August 2001, MTA Bridges and Tunnels began a $286 million overhaul that will bring the Bronx-Whitestone Bridge not only closer to its original design, but also prolong its useful life. In recent years, engineers have discovered that the added weight of the stiffening trusses and the thicker concrete roadway have accelerated wear and tear on cables that were not designed to carry such heavy loads. Upon completion of the project in 2008, the bridge lost 6,000 tons, or one-quarter of its total suspended weight.

The highlights of the Bronx-Whitestone Bridge rehabilitation, which was supervised by Weidlinger Associates, were follows:

The heavy steel Warren stiffening trusses, which were a remedial measure taken to stabilize the bridge in the 1940s, were removed during mid-to-late 2003. To replace the trusses, new lightweight fiberglass fairings were installed during 2004 along each side of the existing plate-girder deck. The eight-foot-high, wedge-like fairings produce the aerodynamic effect of an airplane wing, allowing the wind to circulate around the deck (in effect "slicing" the deck), rather than twist it.

The old bridge deck, which had a 4½-inch-thick concrete roadway, was replaced with an orthotropic deck. The new deck, which has a three-inch-thick roadway, is 40 percent lighter than the old deck. Construction of the new roadway required closure of one lane of traffic at all times. A concrete "zipper" was used to regulate traffic flow: three lanes to the Bronx during the morning rush, and three lanes to Queens during the evening rush. The deck replacement was completed in September 2006. Similar improvements will be made to the approach roadways at a later date.

Improvements were made to the lighting, electrical and drainage systems. New variable message signs also were installed.

MTA Bridges and Tunnels also is conducting the following studies (at a cost of $8 million) in conjunction with the reconstruction project:

The first study will investigate the need to completely replace the main cables on the bridge. This work would include repairing barricade supports, steel connection plates, stringers and floor beams.

The second study will determine underwater scour conditions at the bridge towers, and on this basis, a new fender system will be constructed to protect the towers from ice flows and ship collisions.

Other studies will be conducted to seismically retrofit the towers, and to redesign the anchorages.

Prior to the project, MTA Bridges and Tunnels spent $2.3 million to relocate the Lafayette Avenue entrance and exit ramps just north of the Ferry Point toll plaza. This ramp relocation was undertaken in cooperation with the NYSDOT project to rebuild the nearby "Bruckner interchange."

This 2004 photo of the Bronx-Whitestone Bridge was taken in the same location (Francis Lewis Park) as the 1998 photo above. The trusses were removed and replaced with lighter, more aerodynamic fairings in 2003. (Photo by Steve Anderson.)

SOURCES: "Whitestone Span Opened by Mayor," The New York Times (4/30/1939); "Bridge and Ferry Users Have Rough Crossings" by Emanuel Perlmutter, The New York Times (11/13/1968); Public Works: A Dangerous Trade by Robert Moses, McGraw-Hill (1970); The Power Broker by Robert A. Caro, Vintage Books-Random House (1974); The Bridges of New York by Sharon Reier, Quadrant Press (1977); "A Bridge To Remember," Engineering News-Record (1/21/1982); Great American Bridges and Dams by Donald C. Jackson, Preservation Press-John Wiley and Sons (1988); "Bridge Party: Whitestone Spanning 55 Years of History," Newsday (9/25/1994); Engineers of Dreams by Henry Petroski, Vintage Books-Random House (1995); "A Guide to Civil Engineering Projects in and Around New York City," American Society of Civil Engineers (1997); "Engineer Tracks Bridges' Twists and Turns" by Robin Finn, The New York Times (12/15/2000); Six Bridges: The Legacy of Othmar H. Ammann by Darl Rastorfer, Yale University Press (2000); MTA Bridges and Tunnels Facilities, MTA Bridges and Tunnels (2000); "Call It Whitestone Bridge Lite" by Tom Topousis, New York Post (4/18/2001); "What It Takes To Rebuild a Bridge" by Arnold Ahlert, New York Post (4/20/2001); "A Onetime Thing of Beauty Get a Little Prettying Up" by Alisa Roth, The New York Times (10/12/2003); "A Bridge Too Fat" by Sewell Chan, The New York Times (2/18/2005); "Truck Curb on Two Ailing Bridges" by Joe Mahoney, New York Daily News (6/09/2005); New York Metropolitan Transportation Council; Weidlinger Associates; Dave Frieder; Ralph Herman; Jeff Saltzman; Tom Scannello; Christof Spieler; Stephen Summers; Stéphane Theroux.